their calibration equipment used for pH testing of raw materials, in-process gels, and finished gel products in the Gel Manufacturing unit.

3. Responsibilities

• Operator: To perform cleaning activities after each use.
• Supervisor: To verify and record cleaning status.
• QA: To ensure compliance and validation of cleaning effectiveness.

4. Accountability

The Head of Production and Head of QA are accountable for the implementation and compliance of this SOP.

5. Procedure

5.1 General Instructions

1. Ensure the equipment is switched off and disconnected from power supply (if applicable) before cleaning.
2. Use only approved cleaning agents and materials like lint-free cloths, deionized water, and buffer solutions.
3. Always wear appropriate PPE such as gloves, goggles, and lab coats.

5.2 Cleaning the pH Electrode

1. Immediately after use, rinse the electrode with deionized water to remove residual gel or buffer.
2. If any material adheres to the electrode bulb, gently clean with a soft cloth soaked in pH 7 buffer or electrode cleaning solution.
3. Do not rub or scrub the glass bulb with abrasive materials.
4. Immerse the electrode in freshly prepared electrode storage solution when not in use.

5.3 Cleaning the Calibration Device

1. Wipe the exterior of calibration devices and probes using a lint-free cloth soaked in 70% IPA.
2. For internal components, refer to the device manufacturer’s cleaning instructions.
3. Do not immerse electronic components unless specified safe by the manufacturer.

5.4 Preventive Measures

1. Label each pH meter with the last cleaning and next calibration due date.
2. Store pH meters and calibration devices in their protective casing when not in use.
3. Regularly inspect cables, connectors, and displays for damage or contamination.

5.5 Frequency of Cleaning

• After every use and prior to testing a different sample.
• After exposure to viscous, colored, or strong acidic/basic materials.
• At the end of each shift or batch.

5.6 Documentation

1. Record each cleaning activity in the pH Meter Cleaning Log (Annexure-1).
2. Fill out the Cleaning Checklist for pH Meters and Calibration Devices (Annexure-2).
3. Ensure QA personnel verify and sign off cleaning logs.

6. Abbreviations

• IPA: Isopropyl Alcohol
• QA: Quality Assurance
• PPE: Personal Protective Equipment

7. Documents

1. pH Meter Cleaning Log – Annexure-1
2. Cleaning Checklist for pH Meters – Annexure-2

8. References

• Manufacturer’s Instruction Manual
• GMP Guidelines for Instrument Cleaning
• Internal Quality Management Protocols

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation	Jr. Production Chemist	QA Executive	Head – Manufacturing
Department	Gel Manufacturing	Quality Assurance	Manufacturing

11. Annexures

Annexure-1: pH Meter Cleaning Log

Date	Meter ID	Area of Use	Cleaned By	Verified By	Remarks
		Gel Preparation / In-process / QC

Annexure-2: Cleaning Checklist for pH Meters and Calibration Devices

Step	Status (Yes/No)	Comments	Checked By
Initial rinse with deionized water
Wiping with cleaning solution
Storage solution filled
External device wiped with IPA
Log updated

Revision History

Revision Date	Revision No.	Details	Reason	Approved By
01/06/2022	1.0	Initial release	New SOP	QA Head
02/06/2025	2.0	Added cleaning checklist and frequency update	GMP Update	QA Head